Breathing chest radiography using a dynamic flat-panel detector combined with computer analysis.

Kinetic information is crucial when evaluating certain pulmonary diseases. When a dynamic flat-panel detector (FPD) can be used for a chest examination, kinetic information can be obtained simply and cost-effectively. The purpose of this study was to develop methods for analyzing respiratory kinetics, such as movement of the diaphragm and lung structures, and the respiratory changes in x-ray translucency in local lung fields. Postero-anterior dynamic chest radiographs during respiration were obtained with a modified FPD, which provided dynamic chest radiographs at a rate of 3 frames/s. Image registration for correction of physical motion was followed by measurement of the distance from the lung apex to the diaphragm. Next, we used a cross-correlation technique to measure the vectors of respiratory movement in specific lung areas. Finally, the average pixel value for a given local area was calculated by tracing the same local area in the lung field. This method of analysis was used for six healthy volunteers and one emphysema patient. The results reported here represent the initial stage in the development of a method that may constitute a new method for diagnosing certain pulmonary diseases, such as chronic obstructive pulmonary disease, fibroid lung, and pneumonia. A clinical evaluation of our method is now in progress.